1. Field of the Invention
The present invention relates generally to tape printing devices such as label printers and more particularly pertains to improved label printers, which print alphanumeric characters on a strip of tape and which employ readily replaceable cartridges containing an ink ribbon and a tape strip.
2. Description of the Prior Art
Printing devices such as label tape printers are constructed to enable printed characters to be impressed on a strip of tape. Early such tape printers used print wheel disks having raised characters thereon and were of the "spin and print" manual form wherein the wheel disk was manually rotated to locate the desired character to be printed at the print point. These impact tape printing machines were subsequently modified to be keyboard operated as are typewriters. Such early impact printing devices tended to be large, heavy, cumbersome and slow. These devices have recently been replaced by printers based on thermal printing technology. Present thermal transfer printing uses a heat generating print head having an array of heatable wire pins. By selectively heat activating specific pins to form a sequence of pixels, various printable characters are formed on the ink ribbon for final transfer to a tape strip.
Label tape printers of this type are generally provided with cartridges that contain both the ink ribbon and the tape strip. It is, of course, desirable that such cartridges be readily removable when either the ink ribbon or the tape therein have been depleted and be readily insertable when a fresh cartridge is to be used. In some presently available label tape printers the printing and driving apparatus of the printer device are attached to the printer and removal and reloading of the cartridge requires their disengagement. Such procedure is both complicated and time consuming and in some instances requires the initial opening of the printer and/or cartridge cover to permit the release of the drive means and print head from the cartridge. For these reasons, it is desirable to provide a tape printer and a cartridge therefor in which the cartridge may be readily removed and a new cartridge readily replaced without any complex and time consuming effort.
In known prior art label printers, the tape and ink ribbon cartridge is vertically inserted. In such devices, the print head, and/or feed roller, and/or platen must be displaced to an inoperative position in order to provide clearance for locating and aligning the tape and ink ribbon cartridge in its print and feed positions. Thereafter the print head, feed roller and platen had to be returned to their operative positions. This procedure necessitates time consuming effort and manipulation on the part of the operator.
An example of a prior art label tape printing device incorporating vertical loading of the ribbon and tape cartridge and structure for releasing the print head and drive from the cartridge is U.S. Pat. No. 4,647,235 which discloses a cartridge for a thermal printer that includes a platen and feed rollers for advancing the tape. The prior art devices disclosed in U.S. Pat. Nos. 4,832,514 and 4,836,697 include tape cartridges that are vertically inserted and then moved upon closure of the cover into operative position in the printer housing.
U.S. Pat. Nos. 4,930,913, 4,917,514 and 5,022,771 disclose label tape printers which include vertically directed drive spindles and posts for cooperation with rotatable hubs within the cartridge for controlling and advancing the ribbon and tape within the cartridge. U.S. Pat. No. 5,056,940 discloses a label tape printer device which includes a pivotable cover for closing over and operatively positioning a vertically insertable cartridge. The ink ribbon and tape are advanced by a pair of drive rollers one of which is a part of the printer device and the other is contained within the cartridge. U.S. Pat. No. 4,815,875 discloses structure similar to the above patent but further includes a receiving tray for supporting and positioning the cartridge in its print transfer alignment position. U.S. Pat. No. 5,078,523 discloses a thermal tape printing machine which comprises a cassette receiving area formed as a recess in the rear wall of the printing machine. The recess includes a vertical surface through which extend a print head, a platen, a cassette lock, and a guide pin as well as other elements all for engagement with coacting internal parts of the cassette when the cassette is inserted into the recess.
U.S. Pats. Nos. 3,643,779 and 3,804,227 which relate to typewriters and cartridges therefor disclose laterally insertable typewriter cartridges for feeding ink ribbon to and from an external typewriter print point. The cartridge disclosed does not include a platen nor a tape nor can it accept a print head for internal printing.